‘Twas once written that “public policy is a very unruly horse, and when once you get astride it you never know where it will carry you.”

Or throw you.

If Pittsburgh Mayor Bill Peduto continues to hew to his newly stated public policy regarding the operation and conduct of private business in the erstwhile Steel City, the broncing buck he has chosen to mount surely will leave him -- if not the Greater Pittsburgh economy -- in some orthopedic ward.

The Democrat mayor not so long ago ladled lavish praise on ride-sharing icon Uber. He at least appeared to embrace the veneer of the precept that the best government is the government that governs least -- and embraces innovation.

But now Peduto is expressing second thoughts about the company that has invested hundreds of millions of dollars in the city and created hundreds of high-tech jobs with more likely to follow.

For you see, Uber doesn’t necessarily comport to Peduto’s “progressive” philosophy of “social justice” in pursuit of a new “social contract.” And it sometimes has balked at the Peduto administration’s efforts to shake it down for cash.

It was in an April 3 Wall Street Journal story that Peduto intensified his over-the-bow bombardment of Uber.

“If they are going to be involved in an economic disruption, they have a moral obligation to society,” Peduto said.

It was just last year that the mayor defended the Uber business model against a state Public Utility Commission that, at one point, appeared to be doing the bidding of the monopoly that the taxicab industry had been for so long.

“It’s not our role to throw up regulations or limit companies like Uber,” Peduto told The New York Times.

That was then, this is now.

Peduto somehow now appears to find the rise of Uber -- Its challenge to the taxi monopoly? Its development of self-driving vehicles? Its practice of higher fares in higher demand situations? -- analogous to the rise of Pittsburgh’s steel industry a century ago.

All the bad parts of that rise, that is.

Said the mayor in a statement released a day after The Journal article appeared:

“One hundred years ago, Pittsburgh was the original economic disruptor. We created air dangerous to breathe, water poisonous to drink and the greatest disparity between the haves and have nots in American history.”

Well. It also sowed the seeds for the middle class and produced the steel that thwarted every “ism” that threatened republicanism the world over.

In Peduto’s mind, Uber now is “dangerous” and “poisonous”? Uber somehow is widening the gap between the “haves and have nots”? Then, too, are the Pittsburgh universities and high tech outfits with which Uber has partnered?

This is absurdity writ large. The mayor yelps “Waaaa!” in pursuit of a policy of Waaa-waaa-ism.

The mayor who pummeled those who “throw up regulations” and seek to “limit companies” now seeks to do just that.

Among other things, Peduto says he wants to force Uber to allow drivers to buy group health insurance and to force Uber to make its drivers employees instead of the independent contractors they are.

But that’s a private business decision; it’s not the proper role of government.

He also wants Uber to improve the fuel efficiency of the cars used for ride-sharing. What, there are no government standards now?

And Peduto throws this out: “We understand that not all economic growth benefits society.”

Where, in Ludditeville? What’s next, a Peduto order to bring back elevator operators?

Another group aligned with Peduto even is demanding that Uber share its profits with the city.

What, from each according to his abilities, to each according to his needs?

Again, from Peduto’s April 4 statement:

“In Pittsburgh we have a saying -- if it’s not for all, it’s not for us. That’s in our DNA, that’s who we are.”

Guess we’re all “social Democrats” now, is that it?

Continued Peduto:

“We look forward to working with all companies in building the new economy, sharing our talent and our work ethic. However, we expect our partners to respect our past, just as we do, as we continue to build our future.”

As long as they pay tribute to the “social justice” crowd, is that it Mr. Mayor? Is that now, as Peduto puts it, the “Pittsburgh way of doing business”?

If it is, no business in its right mind should consider doing business in Pittsburgh.

Goodness knows, there already are more than enough government-created impediments to doing business in Pittsburgh and in Pennsylvania. Sadly, the Peduto Manifesto is the latest in a long line of them that wrap around too many decades.